Update delete.md, adding finalizer delete-pxc-pods-in-order

[hieu2102]

The doc is missing finalizers.percona.com/delete-pxc-pods-in-order. This is the default finalizer as of pxc-db version 1.18.0:

• https://artifacthub.io/packages/helm/percona/pxc-db/?modal=values
• https://github.com/percona/percona-xtradb-cluster-operator/blob/main/deploy/cr.yaml

[Copilot]

Pull request overview

This PR updates the deletion documentation to reflect the addition of a new default finalizer (delete-pxc-pods-in-order) introduced in pxc-db version 1.18.0. The changes ensure the documentation accurately describes all available finalizers and their default configuration.

• Updates the finalizer count from 3 to 4
• Adds documentation for the delete-pxc-pods-in-order finalizer
• Clarifies that delete-pxc-pods-in-order is now the default finalizer instead of having all finalizers off by default

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[Copilot]

The clarification '(will not delete PVC)' added to the delete-ssl finalizer is misleading. The delete-ssl finalizer is concerned with SSL-related objects (Secrets, certificates, issuers), not PVCs. This note should only appear on finalizers that could potentially affect PVCs but don't, or should be removed from this line.

Suggested change

	* `finalizers.percona.com/delete-ssl`: if present, objects, created for SSL (Secret, certificate, and issuer) are deleted along with the cluster deletion (will not delete PVC).
	* `finalizers.percona.com/delete-ssl`: if present, objects, created for SSL (Secret, certificate, and issuer) are deleted along with the cluster deletion.